The present invention relates to a cleaning apparatus for cleaning a cylinder in a transfer apparatus (coating apparatus/printing apparatus) which performs transfer (coating/printing) on a transfer target body.
As shown in Japanese Patent Laid-Open No. 2006-56055 , a conventional cleaning apparatus comprises a blanket cylinder which holds and conveys a sheet and transfers varnish supplied from a first varnish supply device to the reverse of the sheet, an upper blanket cylinder which opposes the blanket cylinder and transfers the varnish supplied from a second varnish supply device to the obverse of the sheet, and a cleaning device which collects the varnish by a doctor blade that comes into contact with the circumferential surface of the upper blanket cylinder. In this arrangement, after a feed device feeds the last sheet, varnish supply from the first and second varnish supply devices is stopped, and the varnish remaining on the upper blanket cylinder is cleaned with water supplied to the upper blanket cylinder and collected by the doctor blade.
In the conventional cleaning apparatus described above, when the operation time of the printing press is long, so-called varnish bank is formed during coating, in which the varnish gradually accumulates on the coating start portion of the upper blanket cylinder, that is, on that portion of the upper blanket cylinder which corresponds to the leading edge of the sheet. When the varnish bank is formed, the leading edge of the sheet conveyed by the blanket cylinder adheres to the varnish bank, and a force acts on the sheet in the direction to remove it from the circumferential surface of the blanket cylinder. In this case, the varnish transferred from the blanket cylinder to the reverse of the sheet becomes nonuniform to degrade the coating quality. This problem also occurs in a printing apparatus which prints using high-viscosity ink.